Thursday, 12 January 2012

Earworms: What Makes a Tune Sticky?

Last weekend I had the pleasure of attending a reading of an amazing new musical,One plus One, written by my friends Gil and Sarah Jaysmith. The music from this show has been bouncing around in my head ever since. You’ve certainly had this experience: a fragment of a tune “stuck in your head”, looping over and over. It seems the only possible way to shake this experience is to replace the tune with another, and even that’s only successful some of the time. We call these tunes “earworms” and music that tends to get caught as earworms is known as “sticky”.

But are there really characteristics of music that make it more or less sticky, more or less likely to be an earworm? There is not a lot of research yet about earworms, but it’s starting to crop up in journals about the psychology of music, so I had a quick look to see what’s known.

To start with, scientists tend to call this phenomenon “Involuntary Musical Imagery”, INMI for short. It’s kind of hard to study something that can only be based on people’s verbal reports of its existence, so the studies that are out there all use the technique of simply asking people about their earworm experience. And the studies have shown something you may have guessed: earworms are very common. Over 90% of people reported that they experience earworms at least once a week. About 60% have them at least once a day, and 26% of people have them more than once a day (these numbers are from Liikkanen, 2008).

Recent vs. Sticky

Another interesting study from Finland looked at whether there was a recency effect in earworms. The recency effect is a well-known memory characteristic, in which we’re more likely to remember the last item in a list, rather than an item in the middle, because we’ve seen it more recently and also, no other items have been introduced to interfere with the memory. In this 2009 study, Liikkanen proposed that tunes that we’ve heard most recently are most likely to be stuck in our head. This makes sense to me based on my own experiences: I’ve often had an old pop song stuck in my head and wondered, “Where did that come from?”, but when I thought a little, I remembered that that song had been playing in the grocery store I had visited 10 minutes earlier. I hadn’t even really noticed the song when it was playing, but just hearing it caused it to be stuck in my head almost right away.

Liikkanen performed an internet study using thousands of Finnish internet users, and he triggered earworms by having the particpants complete lyrics to a number of songs. The order in which the songs were presented was varied, so that Liikkanen could test whether the song presented last was more likely to trigger an earworm. After completing the lyrics, the participants did a “filler” exercise for four minutes, and then they were asked if they had experienced any earworms. About 50% had, and the results showed two things. First of all, some songs were just more “sticky” than others, no matter what order they were presented in. But also, the song presented last was more likely to get stuck in the participants’ heads. So yes, there’s a recency effect. But the characteristics of the songs themselves also have an effect on whether they’re likely to get stuck in your head.

On the other hand, a diary study by Beaman and Williams (2010), in which 12 people reported in detail on over 250 earworm episodes, found that only 10 different tunes were experienced as earworms by more than one person. You’d think that if certain tunes were intrinsically very sticky, then these tunes would get stuck in everyone’s head, especially if they were current pop hits or TV themes, or current advertising jingles.

Circumstances

The most recent paper on the topic of earworms, by Williamson and colleagues, looked at the circumstances under which they occur, and amassed a large pool of earworm data from internet users. The researchers were trying to answer the question: “Under what circumstances do earworms occur?”, and their results were interesting. The most common circumstance in which a song got stuck in someone’s head was when it had been heard recently, or heard repeatedly. This jibes with Liikkanen’s 2009 study.

Another common circumstance that triggered an earworm was through association – for example, seeing a picture of Elvis might trigger Blue Suede Shoes, or remembering a high school dance might start Stairway to Heaven playing in your head. Obviously these associations are highly individual. Mood plays a factor too, since certain moods like sadness or stress can trigger certain melodies for some people. In fact, just thinking of whether sadness triggers any melodies for me brought into my head the song I’m so lonesome I could cry, as performed by Holly Cole.

Another experience that was identified as leading to earworms was boredom, when the mind starts to wander. And this I find particularly interesting because I think this is a clue to what parts of the brain might be involved in generating earworms.

The Default-Mode Network

In general music imagery activates the same parts of the brain that are activated when we listen to music. If you imagine hearing a song, it actually activates the auditory cortex just as if you were hearing it. However, involuntary music imagery is probably slightly different, because it tends to occur when we’re not actively thinking about the music. There’s actually a brain network that’s activated when we’re not consciously thinking about anything: the default-mode network, which consists of the medial prefrontal cortex, precuneus, posterior cingulate cortex, inferior parietal cortex, and lateral temporal cortex.

Figure from Buckner et al., 2008

Activity in the neurons in this network goes down when we’re thinking about something, and increases when we’re doing nothing. Activity in the default-mode network is believed to be the neural correlate of mind-wandering. There hasn’t been any research on this yet, but I’d be willing to bet money that your default mode network is active when you’ve got an earworm.

Characteristics of Sticky Songs?

The research on earworms certainly is a start, but I was surprised that I couldn’t find any research that looked at musical characteristics of songs to try to determine what would make a song “sticky” or not. There is a lot of speculation about it, but nothing even close to conclusive.

Here’s my own take on earworms: I have music stuck in my head pretty much all the time, except for when there’s music actually playing, or if I’m busy teaching, talking, or thinking about something. In other words, if my mental effort is directed somewhere, no earworms, at least not that I’m aware of. If I’m doing something that doesn’t require my conscious thoughts, then there’s an internal soundtrack, usually a repeated fragment of a song. What this means is that the earworms are generated when my default mode network is active: when I’m cooking meals or washing dishes, during my 30 minute bike ride to pick up the kids from school, when I’m waiting for a bus, when I’m lying in bed trying to get to sleep.

The default mode network seems to be responsible for working through background thoughts, making connections, making sense of stuff that’s happened recently. And what’s happened to me recently? Well, lots of music. The music that gets stuck in my head the most is music that I’m trying to learn, or trying to make sense of: songs from a new musical I’ve heard, for example. In the last few days, when my earworms haven’t been Jaysmith earworms, my mind’s ear has been working away at the “Mah na Mah na” song from the Muppets. I’ve been teaching this song to my students with the ambitious plan that they will sing it as a combined group at their upcoming piano recital. I still haven’t quite figured out the best way to teach them the rhythms, which are a little complicated, and I also haven’t figured out who will sing which bits, and whether the verses will be improvised scat or sung as written. I’ve also been practicing the piano accompaniment. With all this focus on the song, it’s not at all surprising that it’s the one stuck in my head: I’ve heard it lots recently, and also my conscious mind has several problems to solve with respect to it.

The research on earworms is admittedly pretty limited so far, but a lot of it points to the idea that earworms are all about memory: the tunes that turn into earworms for us are those that are important, heard recently, heard repeatedly, or are triggered by an association with something else. None of this has much to do with the characteristics of the music itself, but anecdotally we certainly find that some music is “stickier” than others. I think this is simply because some music is more memorable than others. Sticky music is tuneful, entertaining, accessible without being predictable, and contains repetition of the themes to help you remember it. The Jaysmith’s music easily has these characteristics, and it’s not surprising that it has a strong tendency for earworm formation.

Memorable music gets remembered, and our default-mode network has us thinking about it when we’re not doing other things. The really interesting question about earworms is why we can’t stop them. Some people have related them to obsessive-compulsive disorder (OCD), in which people have thoughts that they are unable to stop. But no one has shown a relationship between OCD and earworms, so it’s completely unclear whether there is any neurological similarity. Why can’t we stop these bits of tunes from bouncing around in our heads? No one knows. I guess the researchers still have some work to do.

References:

Beaman CP, Williams TI. Earworms (stuck song syndrome): Towards a natural history of intrusive thoughts. British Journal of Psychology. 2010;101(4):637-653.

Liikkanen LA. How the mind is easily hooked on musical imagery. Proceedings of the 7th Triennial Conference of European Socity for the Cognitive Sciences of Music. 2009.

Liikkanen LA. Music in Everymind: Commonality of Involuntary Musical Imagery. Proceedings of the 10th International Conference on Music Perception and Cognition. 2008

Schürmann M, Raij T, Fujiki N, Hari R. Mind’s Ear in a Musician: Where and When in the Brain. NeuroImage. 2002;16(2):434-440.

I'd be interested to hear your views on audiation that occurs with music you've never heard before. Sometimes the (almost incessant) music in my head is stuff I've heard before, but other times it's completely original, as far as I can tell. This is a trait I share with the composer Howard Goodall. I often wonder how common it is. Certainly most people I know seem to think I'm a bit odd because of it - or maybe they just think I'm odd anyway!

About Me

Tara Gaertner is a neuroscientist, music educator, writer and speaker. She holds a Bachelor’s degree in Music from McGill University and a Ph.D. in Neuroscience from the University of Texas, Houston. She has taught piano, flute, and music theory since 1988 and currently teaches the Music for Young Children program as well as private piano and flute lessons. She is an Adjunct Professor at the University of British Columbia, lecturing on Neuroscience in the department of Occupational Science and Occupational Therapy.